Safety-valve



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N. CURTIS.

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2 Sheets-Sheet 2.

N.v CURTIS. Safeaty Valve.

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UNITED STATES PATENT OFFICE.

NELSON CURTIS, OF NEWTON CENTRE, MASSACHUSETTS.

SA FETY-VALVE.

SPECIFICATION forming part of Letters Patent No.` 231,214, dated August 17, 1880.

Application filed November 1D, 1879.

To all whom 'it may conce-ra Be it known that l, NELSON- CURTIS., of.

'reference marked thereon, which drawings forni a part of this specification.

The nature of myiinvention relates to .the improved and novel construction of' a safety or relief valve, whereby the direct pressure is made to act-on a piston or diaphragm so as to open the escape or relief valve with a clear opening, and to hold it thus open luntil the pressure subsides to the given limit, so preventing the escape or relief valve from riding upon or th-rot-tlingthe escaping ilow ot' steam or other iluid, &c., under pressure, substantially as hereinafter more fully set forth.

With reference to the drawings, Figure lis a sectionalA elevation illustrating tbe invention, thel section being taken in a vert-ical plane coinciding with the axes of the valves. Fig. 2 is a plan et' the main or body part containing the induction and eduction passages, the

` relief-valve iiston a. die., with bait' end views attached, and stem F or other suitable means.-

of the same. Fig. 3 is .a view from beneath ot' tbe top part used as an adjusting-screw for spring g. Fig. 4 is a plan of the intermediate part carryingt-he adjusting-screw, &c. Fifa 5 illustrates one of the modications of my improvement deemed practicable to make, and represents, like Fig. 1, a vertical central sectional elevation.

Like letters refer to the saine or corresponding parts in all the figures.

Referring to the drawings, A is an induction passage or pipe. E is an eduction'or escape pipe or passage. a is a piston, to be operated upon by the direct pressure of the steam, fluids, or gases under pressure to which its use is applied. b is the principal or relief valve.

A spring, h, bears the valve b to its seatwith a moderate pressure. The valve is guided in its movements by the piston a, to which it is The pressure nds its equilibrium in cham bers c and D,on both sides of piston a, through the small passage G. A secondary valve, d, furnishes an exhaust or escape for the pressnre in chamber @through passage m 'n to the escape-passage E.

Apassage, L; leads from chamber D or other space containing the direct pressure into the chamber c, Wherev is provided the diaphragm f connected to valve d, so that. when the pressure increases beyond a given liunt it forces the diaphragm f to lift the valve d, giving free exit for the pressure in chamber c out into the escape-passage E through m a. This relieves the pressure in chamber c more promptlyy than it can be maintained by the supply through the diminutive passage G, and gives an immediate preponderance to the pressure in chamber l), which acting on piston a 'forces it back, giving 'fr ce opening to valve b. -In opening valve b the pressure in chamber' D is available on the excess of the area of piston cover that. of valve b.

The passage G in Fig. 1 ma) be made in the piston a, it' preferred.

A spring, g, is arranged to act upon tbe :back ot" diaphragm j', and is adjusted to any required limit oi' pressure by means of 'a suit. able zuljusting-screw, as H H, so that when the pressure in chamber e exceeds this point of adjustment it forces thediaphragm f, compressing-spring g, and lifting-valve d open, as above explained; but when the pressure in A D e falls below the point of adjustment the spring g presses valve d to its seat, when immediately, though not too suddenly, the pressure in chamber e is'brought to an equilibrium of pressure with that of D by means of the small passage G. The valve b is then forced to its seat by the action ofthe restored press ure in chamber c acting upon so much of the piston area as is represented by the area of valve b,'(which valve-area when closed is exposed only to atmospheric pressure,) aided by the recoil of spring h. The required pressure is thus maintained, any excess thereof acting immediately, as before, on diaphragm f, when the same process is repeated.

It will be seenthat when the valve b opens it is not dependent for its open condition upon the action of steam or other iiuid, gas, or liquid rushing under itsface in a throttled condition, but is held up by the direct pressure oi steam IOC in chamber D acting on piston a, and can only close when this same pressure, maintained in chamber e by means of passage L-and acting ou diaphragm f, becomes reduced to the lixed limit, allowing the spring g to act andclose the valve d. When this occurs it. causes the immediate restoration of equal pressure in c and D through p G, as ex# A latch, l, falls into lock-notches in screw H, and the shackle M of a padlock secures it there, thus locking'A the valve against any interference whereby the limit of pressure might be changed, while the lever i furnishes at the same time the means by which'to open the valve d, and thereby the relief-valve b, as cx plained, the safety-valve all the while being, as explained, locked against the possibility of any ones interfering to change the limit of pressure.'

It is obvious that a piston may be substituted for diaphragm j; or a diaphragm snbstitnted for piston a, though at the present stage of experience it is thought with a possible, if not probable, disadvantage.

Fig. 5 illustrates another ofthe modifications deemed practicable to make, in which both piston a and the suggested diaphragm are used together. Thismodiiicationpermitsthevalvebto open in the direction of the flow of steam, &c., which may giveitthe preference with some; but tsadvautagcmay bequestionable until demonstrated by furtherexperience. In this instance,

as see Fig. 5, a small spring, N, inserted be' tween valve d and pistou a, so as to. retard the closing o f valve d somewhat, may be found nscful. In this modication (see Fig. 5) the eqni lihrium-passage G may be seen near the ccnter of piston a. lt may also be made in the piston shown in Fig. l, if preferred, rather than in the case, as shown. This valve is deemed applicable to all the fluids, gases, and liquids employed under pressure, the materials for its construction being selected with reference thereto. For steam brass or the other mate rials usually employed will be found suitable. The small p G can be dispensed with` by making the piston a lit the chamberso freely as to permit the limited transmission of pressure required from'one side to the other.

The internally-threaded part of screwHhas the head 1c, of which it is a part. This head H I: performs several useful functions. Besides forming the ornamental cap-piece, itcarriesthe lock-notches otherwhere referred to. Also, the lever i serves as au adjusting-screw for spring g and as guide for the prolongation ofthestem of valve d.

I claim- Y 1. In a safety-valve having the valve b oper- 6o ated by a piston, n, the case comprising induetOD-passg A, s-: l'. Pm: 1 1;: e E, hmbl' passages m n, andcham'ber when co aud'arranged in combinaton'with the secondary limited-pressure valve d, substantially as and for the purpose set forth.

2. The valved, in combination with the pressure-chamber e, diaphragm or pistou j, spring g, passage L, pressure-ehambereand 1::

G, substantially as described. 7o

3. In a safetywalve, the combination of the valve b and piston awith the springh, arranged to act directly upon the piston a inthe direc tion of the closing of the attached valve b, sub

stantially as shown and described.

4. In a safety-valve, the screw-cap H k, coustrncted to adjust the spring g and carry the lever and notched receiver for detentlever l, in combination with springpa'nd valve d, substantially'as shown and described.

5. In a safety-valve, the screw-capH I gconf structcd to adjust the spring g and carry the lever i and notched receiver for datent-lever! and guide the stem or prolongation thereofof valve d,in combination with valve and spring 85 g, substantially as shown and described.

6. The screw H,'notched to receive detentlever l, in combination with lever l, springg, diaphragm or piston f, and the secondary valve d, substantially as described. 9o

7. In a safety-valve, the detent-leverkwhen provided with the retaining-arm lao-receive the 'shackleof a padlock, in combination with the adjusting-,screw H k, having the receiver for lever l, substantially ns' slim and V95 degcribed' t' al the lati el -large-ans nasaetyw ve, re v y: diaphragm or piston f, when acted upon by direct-.supply pressure, so as to open the small valve d, thereby to open a main reliefvalve, b, roo i in combination with the valve d, substantially as and for thepurpose set forth.

9. In a safetyfvalv'athe, snows-) H 1:,constructed Ate adjust the sprin g carry the notched receiver,. for datent verl, incombil nation with the spring. g and valve d, substantially as described.

h NELSON QUMIS. A Witnesses:

H. J. EDUARDS, D. N. B. 

